Korg M3 with Karma for me the same as arranger but for another type of music. After I get Korg M3 at home (is was October 2007) I since turn on my G-70 two or three times only.
If you want gig with evergreens than you need auto arranger. If you want simply to play with music that contemporary and definitely not evergreens then Karma is sufficient. Style of my Karma playing not very different from that of auto arranger: left hand providing harmony, right hand providing solo. "Styles" exists but this is not "sequenced patterns" with intro and ending. It is very hard to explain it in text. Better you go to a music shop and try with any "combi". It is very interesting to improvise with this "combi".
The only thing that missed in Korg M3 is bossa-nova rithm. I am afraid it because my laziness to download bossa-nova "combi" from yet to be determined source in Internet.
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Roland G-70, Korg M3-73 with Radius, Roland Handsonic HPD-15